Abstract Poly(ether ketone ketone) (PEKK) is a thermoplastic of the poly(aryl ether ketone) (PAEK) family, with excellent mechanical and thermal performances and high chemical resistance properties. This makes it an appealing material in high‐performance applications as a replacement for poly (ether ether ketone) (PEEK). PEKK was thus selected in this study as a base material for application in 3D printing. The effects of nozzle temperature, layer orientation and layer thickness on the final properties of 3D‐printed PEKK parts were investigated. Furthermore, we assessed the mechanical and morphological features of printed samples through tensile tests and scanning electron microscope, respectively. Thermal properties of samples were also evaluated through DSC and DMA analysis. Optimum printing parameters were found at 0.15 mm layer thickness, 380°C nozzle temperature, and [45/−45°] layer orientation. The printed PEKK samples were annealed at various temperatures to allow the relaxation of residual stress and enhance the degree of crystallinity. Samples annealed for 1 h at 240°C have shown an improved elastic modulus by ~14%, tensile strength by 17%, and glass transition temperature by 17.2°C from the increased by 24% degree of crystallinity.
This paper presents a detailed analysis of the effect of the height of the 3D Phoenix Cell on the performance of Metal-Only Reflectarray Antennas. An improved design approach is proposed and a 18% bandwidth (for gain variations less than 1 dB) is obtained after the optimization.
This work aims to improve the powder-bed spreading process for laser powder bed fusion additive manufacturing by gaining a greater understanding of metal powder flowability through numerical modelling and in-situ experimentation.Using the Discrete Element Method (DEM) to study the flowability of the powder and its intrinsic properties. A high-fidelity particle-scale model was developed to capture the dynamics of metal particle interactions in a virtual Hall flow meter based on a modified Beverloo law. The results are validated experimentally using the Hall flow static powder characterisation technique.For SS316L powder alloy with the hall-value of 29s/50g and with an angle of repose (AOR) of 32, the modelled powder that exhibited the same flow behaviour was found using 0.5 for both rolling and sliding coefficients resulting in simulated Hall value of 28.55s/50g with a simulated flow rate of 0.571 g/s, which is validated by AOR of the simulated powder [31.2-32.6]. However, rolling friction had minimal effect on the mass flow rate but increased the angle of repose. Sliding friction significantly decreased the mass flow rate and increased AOR.DEM is an ideal method to study flowability. However, there are certain constraints imposed on the computational power by a number of simulated particles and simulation time-step. Future research may involve investigating other dynamic flowability characterisation techniques.Enabling a better understanding of powder particle flow at a micro-scale by modelling powder flowability. This leads to simulating a more realistic powder bed and improving the powder spreading process, leading to better AM parts quality.This paper provides a unique approach for modelling the flowability of SS316L powder using a Beverloo law-based design of the Hall flow meter. This will improve the modelling of the spreading process needed for metal 3D printing.
This paper presents a metal-only reflectarray antenna made of 3D phoenix cells and its fabrication using additive manufacturing. An electric circuit is proposed for analyzing the behavior and capabilities of the considered cell. The agreement between full-wave simulations and the circuit predictions is very satisfactory when varying the cell geometrical parameters on a large range of values. The simulated gain of the designed reflectarray at 20 GHz is 30.2 dBi with an efficiency of 49.3% and a 1 dB-gain bandwidth of 17.5%. The proposed reflectarray is suitable for working in severe environments due to its metal-only characteristics.
Despite the application of the Additive Manufacturing process and the ability of parts' construction directly from a 3D model, particular attention should be taken into account to improve their mechanical characteristics. In this paper, we present the effect of individual process variables and the strain-rate sensitivity of Onyx (Nylon mixed with chopped carbon fiber) manufactured by Fused Filament Fabrication (FFF), using both experimental and simulation manners. The main objective of this paper is to present the effect of the selected printing parameters (print speed and platform temperature) and the sensitivity of the 3D-printed specimen to the strain rate during tensile behavior. A strong variation of tensile behavior for each set of conditions has been observed during the quasi-static tensile test. The variation of 40 °C in the platform temperature results in a 10% and 11% increase in Young's modulus and tensile strength, and 8% decrease in the failure strain, respectively. The variation of 20 mm·s-1 in print speed results in a 14% increase in the tensile strength and 11% decrease in the failure strain. The individual effect of process variables is inevitable and affects the mechanical behavior of the 3D-printed composite, as observed from the SEM micrographs (ductile to brittle fracture). The best condition according to their tensile behavior was chosen to investigate the strain rate sensitivity of the printed specimens both experimentally and using Finite Element (FE) simulations. As observed, the strain rate clearly affects the failure mechanism and the predicted behavior using the FE simulation. Increase in the elongation speed from 1 mm·min-1 to 100 mm·min-1, results in a considerable increase in Young's modulus. SEM micrographs demonstrated that although the mechanical behavior of the material varied by increasing the strain rate, the failure mechanism altered from ductile to brittle failure.
To provide a comprehensive review of additive manufacturing use in heat transfer improvement and to carry out the economic feasibility of additive manufacturing compared to conventional manufacturing. Heat transfer improvement is particularly interesting for different industrial sectors due to its economic, practical, and environmental benefits. Three heat transfer improvement techniques are used: active, passive, and compound.According to numerous studies on heat transfer enhancement devices, most configurations with strong heat transfer performance are geometrically complex. Thus, those configurations cannot be easily manufactured using conventional manufacturing. With additive manufacturing, almost any configuration can be manufactured, with the added benefit that the produced parts’ surface characteristics can enhance heat transfer. It can, however, lead to a significant pressure drop increase that will reduce the overall performance. In the given article, a comparison of the capital cost of a 100 MW parabolic trough power plant has been carried out, considering two types of solar receivers; the first is manufactured using conventional methods, and the second uses additive manufacturing. The heat transfer of the new receiver configuration is investigated using computational fluid dynamics through ANYS Fluent.Although the cost of additive manufacturing machines and materials is high compared to conventional manufacturing, the outcome revealed that the gain in efficiency when using additive-manufactured receivers leads to a reduction in the number of receiver tubes and the number of solar collectors needed in the solar field It implies a considerable reduction of parabolic trough collector plant capital cost, which is 20.7%. It can, therefore, be concluded that, even if initial setup expenses are higher, additive manufacturing could be more cost-effective than traditional manufacturing.With the reduction of the parabolic trough collector plant capital cost, the levelized cost of electricity will eventually be reduced, which will play a role in increasing the use of solar thermal energy.No review studies discuss the manufacturing potential and cost-effectiveness potential of additive manufacturing when producing heat transfer improvement equipment, especially when producing long pieces. In addition, the paper uses a novel receiver configuration to investigate the economic aspect.
To enhance access to an affordable drinking water source in rural arid areas, emerging solar desalination technologies are extensively investigated mainly solar powered membrane separation techniques. The purpose of this work is to highlight factors promoting the development of thermal water desalination processes including the availability of brackish (BW) aquifers, rainfall, water salinity, hydraulic conductivity, water table depth, and abundant solar irradiance (DNI). This work evolves identification of BW aquifers in arid areas of Morocco, and select ing the most suitable site to build solar thermal desalination plants. To select the best aquifer, hence, the most suitable site; five brackish water (BW) aquifers located in arid regions of Morocco have been identified then compared according to six aforementioned factors using the Analytic Hierarchy Process (AHP). This study revealed that Tafilalet and Errachidia aquifers are the most promising regions for such kind of desalination technologies from both aquifers characteristics and DNI point of view.
In this chapter, an overview parameters and their impact on the final characteristics of 3D-printed parts is presented. This chapter begins by introducing the holistic concept of fused filament fabrication (FFF) process and its principle as an interesting technology for many applications. Then, the basic principles of controlling factors are described. This chapter also highlights the parameters involved in FFF and their interaction with the final properties of the printed components.
Polymer membranes are central to the proper operation of several processes used in a wide range of applications. The production of these membranes relies on processes such as phase inversion, stretching, track etching, sintering, or electrospinning. A novel and competitive strategy in membrane production is the use of additive manufacturing that enables the easier manufacture of tailored membranes. To achieve the future development of better membranes, it is necessary to compare this novel production process to that of more conventional techniques, and clarify the advantages and disadvantages. This review article compares a conventional method of manufacturing polymer membranes to additive manufacturing. A review of 3D printed membranes is also done to give researchers a reference guide. Membranes from these two approaches were compared in terms of cost, materials, structures, properties, performance. and environmental impact. Results show that very few membrane materials are used as 3D-printed membranes. Such membranes showed acceptable performance, better structures, and less environmental impact compared with those of conventional membranes.
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